JP7039886B2 - Image holder, image forming unit, image forming device - Google Patents

Description

The present invention relates to an image holder, an image forming unit, and an image forming apparatus.

The flange for a photoconductor drum described in Patent Document 1 is provided with a conductive arcuate member inside the fitting portion along the outer circumference of a cylindrical portion having a diameter smaller than the fitting portion. Then, the end portion of the arcuate member extends through the notch portion of the cylindrical portion to the center of rotation of the flange, and the tip portion thereof constitutes the contact portion.

Japanese Unexamined Patent Publication No. 11-272121

The image holder has a metal cylindrical base material, a photosensitive layer formed on the outer peripheral surface of the base material, and a metal pressing portion for grounding the image holder. This pressing portion is pressed against the inner peripheral surface of the axial end portion of the base material in the base material.

Here, in order to reduce the cost of the base material, for example, the thickness of the base material may be reduced to a constant level. However, if the thickness of the base material is made constant, the roundness of the base material at the portion where the pressing portion is pressed is lowered.

An object of the present invention is to reduce the roundness of the base material in a configuration in which the pressing portion is pressed against the inner peripheral surface of the base material, while reducing the cost as compared with the case where the thickness of the base material is constant. Is to suppress.

The image holder according to the first aspect of the present invention includes a metal cylindrical base material, a pressing portion pressed against the inner peripheral surface of the base material, and a photosensitive layer formed on the outer peripheral surface of the base material. The thickness of the portion of the base material pressed by the pressing portion is a thick portion that is thicker than the thickness of the other portion, and the thick portion is the base material. It is partially formed in the circumferential direction and extends in the circumferential direction of the base material when viewed from the axial direction of the base material, and the step caused by the difference in the thickness of the base material is the inner peripheral surface of the base material. It is characterized by being formed only in.

In the image holder according to the second aspect of the present invention, in the image holder according to the first aspect , a recess for reducing the thickness of the general portion of the base material is formed on the inner peripheral surface of the base material. The pressing portion is pressed against the inner peripheral surface of the axial end portion of the base material, and the thickness of the thick portion is not more than twice the thickness of the other portion. It is characterized by.

In the image holder according to the third aspect of the present invention, in the image holder according to the first or second aspect, a plurality of the thick portions are formed, and the base material is separated from the thick portions. In the above, another thick portion having a thickness higher than the thickness of the other portion is partially formed in the circumferential direction of the base material, and the shape of the thick portion and the said The shape of the other thick portion is the same, and the thick portion and the other thick portion are arranged at similar intervals in the circumferential direction of the base material.

The image forming unit according to the fourth aspect of the present invention includes the image holder according to any one of the first to third aspects, a charging member that charges the outer peripheral surface of the image holder, and the charged image. It is characterized by comprising a developing member that develops an electrostatic latent image formed by exposing the outer peripheral surface of the holder as a toner image.

The image forming apparatus according to the fifth aspect of the present invention includes the image forming unit according to the fourth aspect and a transfer member for transferring a toner image formed on the outer peripheral surface of the image holder to a recording medium. It is characterized by.

The image forming apparatus according to the sixth aspect of the present invention includes the image holder according to any one of the first to third aspects, a charging member that charges the outer peripheral surface of the image holder, and the charged image. A developing device that develops an electrostatic latent image formed by exposing the outer peripheral surface of the image holder as a toner image, and a transfer member that transfers the toner image formed on the outer peripheral surface of the image holder to a recording medium. It is characterized by having.

According to the image holder according to claim 1 of the present invention, in the configuration in which the pressing portion is pressed against the inner peripheral surface of the base material, the cost is reduced as compared with the case where the thickness of the base material is constant, and the base is used. It is possible to suppress a decrease in the roundness of the material.

According to the image holder of the first aspect of the present invention, the outer diameter of the base material can be the same from one end to the other end in the axial direction of the base material.

According to the image holder of the second aspect of the present invention, the base material can be formed by impact processing and ironing processing.

According to the image holder of the first aspect of the present invention, the weight of the base material can be reduced as compared with the case where the thick portion is formed over the entire circumference of the base material.

According to the image holder of the third aspect of the present invention, the roundness of the base material is compared with the case where the thick portion and the other thick portion are arranged at different intervals in the circumferential direction of the base material. Can be suppressed from decreasing.

According to the image forming unit of the fourth aspect of the present invention, the toner formed on the outer peripheral surface of the image holding body is compared with the case where the image forming unit is provided with the image holding body having a constant thickness of the base material. It is possible to suppress uneven density of an image.

According to the image forming apparatus of the fifth aspect of the present invention, the density unevenness of the output image can be suppressed as compared with the case where the image forming apparatus includes an image holder having a constant thickness of the base material. ..

According to the image forming apparatus of the sixth aspect of the present invention, the density unevenness of the output image can be suppressed as compared with the case where the image forming apparatus includes an image holder having a constant thickness of the base material. ..

It is an enlarged sectional view which showed the image holder which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the image holder which concerns on 1st Embodiment of this invention. It is a perspective view which showed the closing member and the grounding member of the image holding body which concerns on 1st Embodiment of this invention. It is an exploded perspective view which showed the image holder which concerns on 1st Embodiment of this invention. It is a figure which showed the evaluation result of Example 1, Example 2, Example 3, and Comparative Example 1 of the 1st Embodiment of this invention in a table. It is a top view which showed the image holder and the developing apparatus which concerns on 1st Embodiment of this invention. It is a side view which showed the image holder and the developing apparatus which concerns on 1st Embodiment of this invention. (A) (B) (C) It is a process diagram which showed the manufacturing process of the base material which constitutes the image-bearing body which concerns on 1st Embodiment of this invention. (A) (B) It is a process diagram which showed the manufacturing process of the base material which constitutes the image-bearing body which concerns on 1st Embodiment of this invention. It is a perspective view which showed the punch type and the ironing type used for manufacturing the base material which comprises the image holder which concerns on 1st Embodiment of this invention. (A) (B) (C) It is a process diagram which showed the manufacturing process of the base material which constitutes the image-bearing body which concerns on 1st Embodiment of this invention. (A) (B) (C) It is a process diagram which showed the manufacturing process of the base material which constitutes the image-bearing body which concerns on 1st Embodiment of this invention. (A) (B) (C) It is a process diagram which showed the manufacturing process of the base material which constitutes the image-bearing body which concerns on 1st Embodiment of this invention. It is a schematic block diagram which showed the image forming apparatus and the image forming unit which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the base material which comprises the image-bearing body which concerns on 2nd Embodiment of this invention.

<First embodiment ( reference embodiment )>
An example of the image holder, the image forming unit, and the image forming apparatus according to the first embodiment ( reference embodiment ) of the present invention will be described with reference to FIGS. 1 to 14. The arrow H shown in the figure indicates the device vertical direction (vertical direction), the arrow W indicates the device width direction (horizontal direction), and the arrow D indicates the device depth direction (horizontal direction).

(overall structure)
As shown in FIG. 14, the image forming apparatus 10 according to the present embodiment conveys the accommodating portion 14 accommodating the sheet member P as a recording medium and the accommodating portion P accommodating the accommodating portion 14. A unit 16 is provided. Further, the image forming apparatus 10 is provided with an image forming unit 20 that forms an image on the sheet member P conveyed from the accommodating unit 14 by the conveying unit 16, and a control unit 48 that controls each unit.

[Accommodation]
The accommodating portion 14 is provided with an accommodating member 14A that can be pulled out from the apparatus main body 10A of the image forming apparatus 10 toward the front side in the depth direction of the apparatus, and the seat member P is loaded on the accommodating member 14A. Further, the accommodating portion 14 is provided with a delivery roll 14B for delivering the sheet member P loaded on the accommodating member 14A to the transport path 28 constituting the transport unit 16.

[Transport section]
The transport unit 16 is provided with a plurality of transport rolls (reference numerals omitted) for transporting the sheet member P along the transport path 28 to which the sheet member P is transported.

[Image forming part]
The image forming unit 20 includes four image forming units 18Y, 18M, 18C, 18K of yellow (Y), magenta (M), cyan (C), and black (K), and exposure light to an image holder 26 described later. An exposure device 42 for irradiating the light is provided. In the following description, if it is not necessary to distinguish Y, M, C, and K, Y, M, C, and K may be omitted.

The image forming unit 18 (process cartridge) of each color is detachable from the apparatus main body 10A, respectively. The image forming unit 18 of each color is provided with an image holding body 26 and a charging member 38 for charging the surface of the image holding body 26. Further, the image forming unit 18 is provided with a developing device 36 that develops an electrostatic latent image formed by irradiating the charged image holder 26 with exposure light and visualizes it as a toner image. There is. The details of the image holder 26 will be described later.

Further, the image forming unit 20 includes an endless transfer belt 22 that circulates in the direction of arrow A in the figure, and a primary transfer roll 44 that transfers the toner image formed by the image forming unit 18 of each color to the transfer belt 22. It is prepared. Further, the image forming unit 20 heats and pressurizes the secondary transfer roll 46 that transfers the toner image transferred to the transfer belt 22 to the sheet member P and the sheet member P to which the toner image is transferred to obtain the toner image. Is provided with a fixing device 50 for fixing the toner to the sheet member P. The secondary transfer roll 46 is an example of a transfer member.

(Action of image forming device)
In the image forming apparatus 10, an image is formed as follows.

First, the charging member 38 of each color uniformly negatively charges the surface of the image holder 26 of each color at a predetermined potential. Subsequently, the exposure apparatus 42 irradiates the surface of the charged image holder 26 of each color with exposure light to form an electrostatic latent image. As a result, an electrostatic latent image is formed on the surface of the image holder 26 of each color. Further, the developing device 36 for each color develops this electrostatic latent image and visualizes it as a toner image. Further, the toner images formed on the surface of the image holder 26 of each color are sequentially transferred to the transfer belt 22 by the primary transfer roll 44.

Therefore, the sheet member P sent out from the accommodating member 14A to the transfer path 28 by the delivery roll 14B is sent out to the transfer position T where the transfer belt 22 and the secondary transfer roll 46 come into contact with each other. At the transfer position T, the sheet member P is conveyed between the transfer belt 22 and the secondary transfer roll 46, so that the toner image of the transfer belt 22 is transferred to the sheet member P.

Further, the toner image transferred to the sheet member P is fixed to the sheet member P by the fixing device 50. Then, the sheet member P on which the toner image is fixed is discharged to the outside of the apparatus main body 10A.

(Main part composition)
Next, the structure of the charging member 38, the developing device 36, the image holder 26, and the method of manufacturing the base material 80 constituting the image holder 26 will be described.

[Charging member 38]
As shown in FIG. 7, the charging member 38 is arranged below the image holder 26. The charging member 38 includes a shaft member 92 extending in the depth direction of the device, and an elastic portion 94 having a cylindrical shape and through which the shaft member 92 penetrates. The shaft member 92 is rotatably supported by a support member 98 that forms a part of the housing of the image forming unit 18. Further, the outer peripheral surface of the elastic portion 94 is in contact with the image holder 26. Then, a voltage is applied to the shaft member 92, and the charging member 38 is driven by the rotating image holder 26 to rotate, so that the charging member 38 charges the surface of the image holder 26.

[Developer 36]
As shown in FIG. 6, the developing device 36 is arranged on one side (lower side in the drawing) in the width direction of the device with respect to the image holding body 26, holds the developer, and is in contact with the image holding body 26. A developing roll 74 in which a developing gap (gap) is formed between the developing rolls 74 is provided. Further, the developing device 36 includes a shaft member 78 constituting the rotating shaft of the developing roll 74 and a pair of adjusting rolls 76.

Further, the shaft member 78 is rotatably supported by the support member 98. Further, the pair of adjusting rolls 76 are attached to the shaft member 78 so as to sandwich the developing roll 74 from the depth direction of the device. The pair of adjusting rolls 76 have the same configuration as each other, and the outer diameter of each adjusting roll 76 is larger than the outer diameter of the developing roll 74.

In this configuration, the outer peripheral surfaces of the pair of adjustment rolls 76 are in contact with the image holder 26, so that a development gap (gap) is formed between the development roll 74 and the image holder 26.

[Image holder 26]
As shown in FIGS. 2 and 4, the image holder 26 has a device depth direction as an axial direction, and includes a cylindrical base material 80 extending in the device depth direction. Further, the image holder 26 has a closing member 82 that is fitted to the front end of the base material 80 in the depth direction of the device to close the opening of the base material 80, and the back side of the base material 80 in the depth direction of the device. It is provided with a closing member 84 that is fitted to the end portion of the base material and closes the opening of the base material 80. Further, the image holder 26 is formed on a shaft member 54 constituting the rotation axis of the image holder 26, a grounding member 64 for grounding the image holder 26, and an outer peripheral surface 80B of the base material 80, and light is emitted. It includes a photosensitive layer 86 that is irradiated to change its properties to form an electrostatic latent image.

-Base material 80, photosensitive layer 86-
The base material 80 is formed in a cylindrical shape using aluminum as an example, and has an outer diameter of 30 [mm], a length of 253 [mm], and a thickness of 0.4 [mm]. Further, in the inner portion of the base material 80 in the depth direction of the device, a thick portion 60 whose thickness is thicker than the thickness of the general portion (an example of another portion) is formed on the entire circumference of the base material 80. It is formed over. Specifically, the thick portion 60 is formed by reducing the inner diameter of the base material 80, and a step is formed in a portion of the inner peripheral surface 80A of the base material 80 where a difference in the thickness of the base material 80 occurs. 72 is formed. That is, there is no step on the outer peripheral surface 80B of the base material 80, and the outer diameter of the base material 80 is the same from one end to the other end in the depth direction of the device.

As an example, the thickness of the thick portion 60 is thicker than the thickness of the general portion (0.4 [mm] in this embodiment), and is 0.8 [mm] (twice as much as 0.4 [mm]) or less. The thick portion 60 is formed over a range of 7 [mm] (L1 in the figure) from the end portion of the base material 80. As described above, the axial length of the thick portion 60 is the same over the entire circumference. In the present embodiment, the thick portion 60 is formed by increasing the thickness, but the thickness of the thick portion 60 may be higher than that of the general portion, and the rigidity may be increased by attaching another member. It may be higher. Further, in the thick portion 60, the length from the end portion of the base material 80 may be any length as long as the free end of the selvage portion 66B, which will be described later, can be in contact with the thick portion 60, and the image formation in which the image is formed. It may be long enough not to fit in the area.

The thickness of the base material 80 is described as 0.4 [mm], but the thickness of the base material 80 is 0.35 [mm] or more and 0.45 [mm] or less in consideration of manufacturing variations. Is. That is, the "thickness 0.4 [mm] of the base material 80" means that the thickness of the base material 80 is 0.35 [mm] or more and 0.45 [mm] or less. As described above, since the thickness of the base material 80 is 0.4 [mm], the mass is lighter than that of the conventional base material having a thickness of 0.7 [mm], for example. The cost has been reduced. In other words, the cost of the image holder 26 is reduced as compared with the case of using a base material having a thickness of 0.7 [mm].

In this configuration, the outer peripheral surface of one of the adjusting rolls 76 provided in the developing apparatus 36 described above is in contact with the outer peripheral surface of the image holder 26 in the thick portion 60 in the base material 80 (see FIG. 6).

The photosensitive layer 86 is formed by providing a photosensitive layer containing a charge generating material that is irradiated with light to generate charges on the outer peripheral surface 80B (see FIG. 2). Further, the region where the electrostatic latent image is formed by irradiating the charged photosensitive layer 86 with light (image forming area) is one side in the device width direction (left side in FIG. 2) as compared with the thick portion 60. ) Part. That is, the photosensitive layer 86 of the portion covering the thick portion 60 is outside the region where the electrostatic latent image is formed (image forming area).

-Closed member 82, closed member 84-
The closing member 82 is formed by using a polycarbonate resin as an example, and as shown in FIGS. 6 and 7, a part of the closing member 82 is inserted into the base material 80 to form a base material. It is fitted to the end of 80. In this state, the closing member 82 closes the opening of the base material 80.

The closing member 82 is in contact with the through hole 82A through which the shaft member 54 penetrates, the contact surface 82B to which the end surface of the base material 80 is abutted in the axial direction of the base material 80, and one end of the contact surface 82B. It has an inner peripheral surface 80A of the base material 80 and a facing surface 82C facing the inner peripheral surface 80A. Further, the closing member 82 has a conical surface 82D whose one end is in contact with the facing surface 82C and whose outer diameter gradually decreases.

The diameter of the through hole 82A is set to 5 [mm] as an example. Then, by passing the shaft member 54, which will be described later, through the through hole 82A, the closing member 82 rotates integrally with the shaft member 54. Further, an adhesive (for example, a cyanoacrylate adhesive) is applied to a portion of the base material 80 facing the facing surface 82C. Then, the facing surface 82C is adhered to the base material 80 by this adhesive, so that the closing member 82 is attached to the base material 80.

The closing member 84 is formed by using a polycarbonate resin as an example, and as shown in FIGS. 2 and 3, a part of the closing member 84 is inserted into the base material 80 to form a base material. It is fitted to the end of 80. In this state, the closing member 84 closes the opening of the base material 80.

The closing member 84 is in contact with the through hole 84A through which the shaft member 54 penetrates, the contact surface 84B to which the end surface of the base material 80 is abutted in the axial direction of the base material 80, and one end of the contact surface 84B. It has an inner peripheral surface 80A of the base material 80 and a facing surface 84C facing the inner peripheral surface 80A. Further, the closing member 84 has one end in contact with the facing surface 84C and is surrounded by a conical surface 84D whose outer diameter gradually decreases and an end edge of the conical surface 84D, and has a circular shape facing the closing member 82 side. It has a circular surface 84E.

The diameter of the through hole 84A is set to 5 [mm] as an example. Then, by passing the shaft member 54, which will be described later, through the through hole 84A, the closing member 84 rotates integrally with the shaft member 54.

Further, an adhesive (for example, a cyanoacrylate adhesive) is applied to a portion of the base material 80 facing the facing surface 84C. Then, the facing surface 84C is adhered to the base material 80 by this adhesive, so that the closing member 84 is attached to the base material 80.

-Shaft member 54-
A conductive SUM-Ni shaft (a shaft obtained by nickel-plating sulfur free-cutting steel) is used for the shaft member 54, and as an example, the outer diameter is 5 [mm] and the total length is 355 [mm]. .. Then, both ends of the shaft member 54 are rotatably supported by the support member 98 as shown in FIG. 7. Further, the shaft member 54 is electrically connected to a metal frame (not shown) and is grounded.

Further, a gear 90 constituting the image forming unit 18 is attached to one end of the shaft member 54, and the rotational force from the motor 88 provided in the image forming apparatus 10 is imaged via the gear 90. It is transmitted to the holder 26.

-Grounding member 64-
As shown in FIGS. 2 and 3, the grounding member 64 is arranged on the closing member 82 side of the closing member 84, and is arranged inside the base material 80. The grounding member 64 has a metal plate-shaped grounding plate 66 and a pair of resin-made rectangular parallelepiped conductive members 68.

As an example, the ground plate 66 is formed by trimming a SUS304-CSP tempering symbol H (JIS G 4313: 1996) having a thickness of 0.2 [mm] into a predetermined shape and bending it. It has a circular main body portion 66A, a pair of ear portions 66B, and a pair of cut-out portions 66C. The selvage portion 66B is an example of a pressing portion.

The outer diameter of the main body portion 66A is the same as the outer diameter of the circular surface 84E of the closing member 84, and the main body portion 66A is overlapped with the circular surface 84E of the closing member 84. Then, the grounding member 64 is attached to the closing member 84 by fixing the fixing portion (not shown) of the main body portion 66A to the fixed portion (not shown) of the circular surface 84E. Specifically, the main body 66A is fixed to the circular surface 84E so that the main body 66A does not float from the circular surface 84E.

A pair of selvage portions 66B are provided so as to sandwich the center of the circular main body portion 66A, and each selvage portion 66A closes a portion protruding in the radial direction of the main body portion 66A from the outer peripheral edge of the main body portion 66A. It is formed by bending toward the member 84 side. As described above, the selvage portion 66B is in a cantilever state. Then, the tip (free end) of the selvage portion 66B is pressed against the thick portion 60 of the base material 80 (see FIG. 2). That is, the selvage portion 66B is a leaf spring.

The selvage portion 66B has a rectangular shape in which R is formed (rounded) at the corner portion of the free end. The width of the selvage portion 66B (L2 in the figure) is 3 [mm], and the length of the selvage portion 66B (L3 in the figure) is 3.5 [mm].

A pair of cut-up portions 66C are provided so as to sandwich the center of the circular main body portion 66A, and each cut-up portion 66C is surrounded by the outer peripheral edge of the main body portion 66A and is similar to the main body portion 66A. It is formed by cutting up a portion arranged in a plane shape on the side opposite to the closing member 84.

Specifically, the cut-up portion 66C is in a cantilever state by cutting up the central side of the circular main body portion 66A. Further, when viewed from the device depth direction (plate thickness direction of the main body portion 66A), the facing direction of the pair of cut and raised portions 66C intersects the facing direction of the pair of selvage portions 66B.

The conductive member 68 is formed in a rectangular parallelepiped shape using a resin material having conductivity. A pair of the conductive members 68 are provided, and the pair of the conductive members 68 are attached to the surfaces of the pair of cut-and-raised portions 66C on the sides facing each other by using a mounting tool (not shown). In this state, the continuity between the conductive member 68 and the raised portion 66C is ensured. Then, as shown in FIG. 1, the pair of conductive members 68 are pressed against the outer peripheral surface 54A of the shaft member 54 by the cut-up portion 66C, respectively.

In this way, by pressing the selvage portion 66B of the grounding member 64 against the inner peripheral surface 80A of the base material 80 and pressing the conductive member 68 of the grounding member 64 against the outer peripheral surface 54A of the shaft member 54, the base material 80 (image). The holding body 26) is grounded.

The "resin material having conductivity" is a resin material having a volume resistivity of 10 ¹⁰ [Ω · cm] or less. In the present embodiment, a polyacetal resin conductive grade (POM EW-02) is used as the "resin material having conductivity".

[Manufacturing method of base material 80]
Next, a method for manufacturing the base material 80 will be described. The base material 80 is manufactured including an impact process for forming a cylindrical cylindrical material 206 and an ironing process for straightening the cylindrical material 206 to form the base material 80.

-Impact processing-
In the impact processing, a bottomed and cylindrical cylindrical material 206 is formed from the slag 202, which is a mass of aluminum. For impact processing, as shown in FIG. 8A, the concave type 204 containing the slag 202, which is a lump of aluminum, and the slag 202 contained in the concave type 204 are pressed to form the slag 202 into a cylindrical shape. A cylindrical punch type 200 is used. The concave portion 204A of the concave type 204 has a circular shape, and the inner diameter of the concave portion 204A is 32.0 [mm] as an example. The outer diameter of the punch type 200 is set to 30.6 [mm] as an example.

In the impact step, first, the slag 202 is housed in the concave mold 204, and further, the punch mold 200 is arranged above the concave mold 204 (see FIG. 8A).

Next, as shown in FIGS. 8B and 8C, the punch mold 200 moves downward to crush and deform the slag 202 housed in the concave mold 204. As a result, the slag 202 is deformed into a bottomed and cylindrical cylindrical member 206 along the peripheral surface of the punch mold 200. As an example, the thickness of the cylindrical material 206 is 0.7 [mm], and the inner diameter is 30.6 [mm].

Next, the punch mold 200 moves upward, and as shown in FIG. 9A, the cylindrical member 206 in close contact with the punch mold 200 separates from the concave mold 104. Further, the cylindrical member 206 is pulled out (demolded) from the punch mold 200 as shown in FIG. 9B.

-Squeezing-
In the ironing process, the thickness of the cylindrical material 206 is reduced to correct the shape of the cylindrical material 206. For ironing, as shown in FIG. 10, a punch type 220 inserted into the cylindrical material 206 (see FIG. 9B) from the tip (lower end in the figure) and an inner peripheral surface 206A of the cylindrical material 206 (FIG. 9). A squeeze type 222 that imitates the outer peripheral surface 220A of the punch type 220 (see 9 (B)) is used. Further, a reduced diameter portion 224 having a smaller diameter than other portions is formed at the tip portion of the punch mold 220.

The punch type 220 has a columnar shape extending in the vertical direction (one direction), and as an example, the outer diameter of the punch type 220 is 29.2 [mm]. Further, the outer diameter of the reduced diameter portion 224 is set to 28.6 [mm]. Further, the ironing type 222 has an annular shape, and as an example, the inner diameter is 30.0 [mm].

In the ironing process, first, as shown in FIG. 11A, the punch mold 220 is inserted into the inside of the cylindrical material 206 from the tip. In FIGS. 11A, 11B, 12C, and 12A, 12B, there is a gap between the outer peripheral surface of the punch type 220 excluding the reduced diameter portion 224 and the inner peripheral surface of the cylindrical material 206. Illustration is omitted.

Next, FIGS. 11 (B) (C) and 12 (A) (B) (C) show from the position where the cylindrical member 206 into which the punch mold 220 is inserted is moved above the ironing die 222. As such, it is moved downward and passed through the inside of the ironing die 222. As a result, the ironing mold 222 presses the cylindrical material 206 against the outer peripheral surface 220A of the punch mold 220 to reduce the thickness of the cylindrical material 206, and further, the inner peripheral surface 206A of the cylindrical material 206 is the outer peripheral surface of the punch mold 220. Follow surface 220A. Then, the tip of the cylindrical member 206 follows the reduced diameter portion 224 to form a portion having a thick wall portion 60 thicker than the general portion (other portion) (see FIG. 12A).

Next, the cylindrical member 206 is pulled out (demolded) from the punch mold 220 as shown in FIGS. 13 (A) and 13 (B). Further, the lower end of the cylindrical material 206 is cut off, and as shown in FIG. 13C, a cylindrical base material 80 having both ends open is formed.

(Action of main part composition)
Next, the operation of the main part configuration will be described.

First, the motor 88 shown in FIG. 7 rotates the image holder 26. As the image holder 26 rotates, the charging member 38 is driven by the image holder 26 to rotate. Further, a voltage is applied to the shaft member 54 of the charging member 38 from a power source (not shown).

Further, as shown in FIGS. 1 and 2, the base material 80 constituting the image holder 26 is electrically connected to the shaft member 54 via the grounding member 64, so that the image holder 26 is grounded. ing. Therefore, a current flows between the charging member 38 and the image holder 26, and the surface of the image holder 26 is uniformly charged. Then, an electrostatic latent image is formed on the surface of the charged image holder 26 by irradiation with the exposure light of the exposure apparatus 42 (see FIG. 14).

Further, the developing device 36 shown in FIG. 6 develops an electrostatic latent image formed on the image holder 26 and visualizes it as a toner image. Specifically, when the outer peripheral surfaces of the pair of adjustment rolls 76 of the developing device 36 are in contact with the image holding body 26, a developing gap (gap) is created between the developing roll 74 of the developing device 36 and the image holding body 26. It is formed. Then, the toner is passed to the electrostatic latent image from this development gap, and the electrostatic latent image is visualized as a toner image.

(evaluation)
Next, the evaluation performed on the image holder 26 according to the embodiment of the first embodiment and the image holder according to the comparative example will be described.

[Each configuration]
First, the configurations of Examples 1, 2, 3 and Comparative Example 1 will be described. Items not described below are all the same among the members.

Example 1 ⇒ The image holder 26 of Example 1 has an outer diameter of 30 [mm], a length of 253 [mm], a thickness of a general portion of 0.4 [mm], and a thickness of a thick portion 60 of 0. A base material 80 having a thickness of 0.7 [mm] and an axial length of the thick portion 60 of 7 [mm] was used.

The production of this base material will be described below. First, using JIS A1050 series (aluminum (AL) purity: 99.5%) slag, a cylindrical material with an outer diameter of 32 [mm], a length of 200 [mm], and a thickness of 0.7 [mm] is processed by impact processing. Manufactured.

Next, ironing is performed using an ironing die 222 with an inner diameter of 30 [mm] and a punching die having an outer diameter of 28.6 [mm] of the reduced diameter portion 224 and an outer diameter of 29.2 [mm] of another part. Was done. The outer diameter is 30 [mm], the length is 300 [mm], the thickness of the general portion is 0.4 [mm], the thickness of the thick portion 60 is 0.7 [mm], and the axial length of the thick portion 60. A cylindrical material having a size of 10 [mm] was produced. Then, both ends were cut to obtain the above-mentioned base material.

Example 2 ⇒ The image holder 26 of Example 2 has an outer diameter of 30 [mm], a length of 253 [mm], a thickness of a general portion of 0.4 [mm], and a thickness of a thick portion of 0. A base material 80 having a thickness of 6 [mm] and an axial length of 7 [mm] in the thick portion was used.

The production of the second embodiment is the same as that of the first embodiment except that the outer diameter of the reduced diameter portion 224 of the punch type is 28.8 [mm].

Example 3 ⇒ The image holder 26 of Example 3 has an outer diameter of 30 [mm], a length of 253 [mm], a thickness of the general portion of 0.4 [mm], and a thickness of the thick portion 60 of 0. A base material 80 having a thickness of .5 [mm] and an axial length of the thick portion 60 of 7 [mm] was used.

The production of the third embodiment is the same as that of the first embodiment except that the outer diameter of the reduced diameter portion 224 of the punch type is 29.0 [mm].

Comparative Example 1 ⇒ For the image holder 26 of Example 3, a base material having an outer diameter of 30 [mm], a length of 253 [mm], and a thickness of 0.4 [mm] was used.

The production of Comparative Example 1 is the same as that of Example 1 except that the reduced diameter portion 224 is not formed in the punch mold.

〔Evaluation item〕
-Roundness evaluation: Roundness of the outer peripheral surface of the base material of the portion where the tip (free end) of the selvage portion 66B is pressed against the image holders of Examples 1, 2, 3 and Comparative Example 1. (JIS B 0419) was measured. The roundness of the base material before attaching the closing member 84 was 11 [μm] or more and 14 [μm] or less. Regarding the roundness, the case of 30 [μm] or less was evaluated as “◯”, and the case of greater than 30 [μm] was evaluated as “x”. Considering the past results, when the roundness is 30 [μm] or less at the part measured this time, the density unevenness of the output image caused by the roundness is at an acceptable level in terms of commerciality. ..

The roundness was measured using a roundness measuring device Rondocom (manufactured by Tokyo Seimitsu Co., Ltd.).

Density unevenness evaluation: The image retainers of Examples 1, 2, 3 and Comparative Example 1 were attached to a Docu Print C1100 manufactured by Fuji Xerox Co., Ltd., and a halftone image with an image density of 50% was output using this image forming apparatus. did. Then, the density unevenness of the output image was visually evaluated. Regarding the evaluation, "○" was found when no concentration unevenness occurred, "△" was found when the density unevenness was acceptable, and "△" was found when the concentration unevenness was acceptable. The case where it cannot be done is marked as "x". By performing this evaluation, the relationship between roundness and uneven density was reconfirmed.

〔Evaluation results〕
The evaluation results will be described with reference to the table shown in FIG. Regarding the roundness evaluation, the roundness of Example 1 is “○” at a roundness of 15 [μm], the roundness of Example 2 is “○” at a roundness of 17 [μm], and the roundness of Example 3 is true. It was "○" at a circularity of 28 [μm]. On the other hand, in Comparative Example 1, the roundness was 38 [μm] and the value was “x”.

Regarding the density unevenness evaluation, it was “◯” for Examples 1 and 2, and “Δ” for Example 3. On the other hand, in Comparative Example 1, it was "x".

(summary)
As can be seen from the above evaluation results, in the image holder 26, the ear portion 66B is pressed against the inner peripheral surface 80A of the base material 80, as compared with the case where the thickness of the base material is constant (Comparative Example 1). Therefore, the cost is reduced and the roundness of the base material is suppressed from being lowered.

Further, the thick portion 60 is formed on the inner peripheral surface 80A of one end portion in the axial direction of the base material 80. Further, the thickness of the thick portion 60 is thicker than 0.4 [mm] and is 0.8 [mm] or less, which is 2 of the thickness of the general portion (other portion) of 0.4 [mm]. It is less than double. Therefore, the base material 80 is formed by impact processing and ironing processing. That is, the base material 80 is molded without using a cutting process.

Further, the step 72 generated by the difference in thickness in the base material 80 is formed on the inner peripheral surface 80A of the base material 80. As a result, there is no step on the outer peripheral surface 80B of the base material 80, and the outer diameter of the base material 80 is the same from one end to the other end in the depth direction of the device.

Further, in the base material 80, the thick portion 60 having a thicker thickness is formed over the entire circumference of the base material 80. Therefore, when the closing member 84 is attached to the base material 80, the closing member 84 is attached to the base material 80 without positioning the closing member 84 in the circumferential direction with respect to the base material 80 in the circumferential direction of the base material 80. ..

Further, the axial length of the thick portion 60 is the same over the entire circumference of the base material 80. Therefore, it is possible to prevent the roundness of the base material 80 from fluctuating at different positions in the axial direction as compared with the case where the length of the thick portion 60 in the axial direction is different.

Further, in the image forming unit 18, the density unevenness generated in the toner image formed on the image holding body 26 is suppressed as compared with the case where the image holding body 26 is not provided.

Further, in the image forming unit 18, the outer peripheral surface of one of the adjusting rolls 76 is in contact with the portion of the thick portion 60 in the base material 80. Therefore, the development gap (gap) between the development roll 74 and the image holder 26 is larger than that in the case where the outer peripheral surface of one of the adjustment rolls 76 is in contact with a portion different from the thick portion 60. Dispersion is suppressed in the depth direction of the device. As a result, the density unevenness that occurs in the toner image formed on the image holder 26 is suppressed.

Further, in the image forming apparatus 10, the density unevenness generated in the output image is suppressed as compared with the case where the image holder 26 is not provided.

<Second Embodiment>
Next, an example of the image holder, the image forming unit, and the image forming apparatus according to the second embodiment of the present invention will be described with reference to FIG. In addition, about the 2nd Embodiment, the part different from the 1st Embodiment will be mainly described.

As shown in FIG. 15, the thick portion 260 of the base material 280 of the second embodiment is partially formed in the circumferential direction of the base material 280. Further, apart from this thick portion 260, another thick portion 270 is partially formed on the base material 280 in the circumferential direction of the base material 280.

A pair of thick portions 260 are provided so as to sandwich the center of the base material 280. The thick portion 260 and the other thick portion 270 have the same shape, and the thick portion 260 and the other thick portion 270 have the same spacing (pitch) in the circumferential direction of the base material 280. It is arranged in.

As described above, since the thick portion 260 is partially formed in the circumferential direction of the base material 280, the thick portion is formed over the entire circumference of the base material, as compared with the case where the thick portion is formed over the entire circumference of the base material. It will be lighter.

Further, the thick portion 260 and the other thick portion 270 have the same shape, and the thick portion 260 and the other thick portion 270 are arranged at the same intervals in the circumferential direction of the base material 280. ing. Therefore, the decrease in the roundness of the base material 280 is suppressed as compared with the case where the thick portion 260 and the other thick portion 270 are arranged at different intervals in the circumferential direction of the base material 280.

The base material 280 can be formed by impact processing and ironing by changing the shape of the reduced diameter portion of the punch type 220 (see FIG. 10).

Further, the other actions of the second embodiment are the same as the actions of the first embodiment except for the action of forming the thick portion over the entire circumference of the base material.

Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. That is clear to those skilled in the art. For example, in the above embodiment, the thick portions 60 and 260 are formed at the axial ends of the base materials 80 and 280, and the thickness of the thick portions 60 and 260 is the thickness of the general portion (other portion). Although it was less than twice the thickness, the thick portion may be formed on the center side of the base material, and the thickness of the thick portion may be larger than twice the thickness of the general portion. However, in these cases, it becomes difficult to mold the base material by impact processing and ironing processing.

Further, in the above embodiment, the axial lengths of the thick portions 60 and 260 are the same over the entire circumference, but the axial lengths may be different. However, in this case, the effect that the thick portion 60 and 260 have in the axial direction is the same over the entire circumference does not play an effect.

Further, in the second embodiment, the shapes of the thick portion 260 and the other thick portion 270 are the same, and the thick portion 260 and the other thick portion 270 are formed at the same intervals in the circumferential direction. However, they may be formed at different intervals. However, in this case, the effect of being formed at similar intervals is not exhibited.

Further, although not particularly described in the second embodiment, the distance between the adjacent thick portion 260 and the other thick portion 270 may be shorter than the width of the selvage portion 66B. As a result, when the closing member 84 is attached to the base material 280, the selvage portion 66B has a thick portion 260 or another thick wall portion without positioning the closing member 84 with respect to the base material 280 in the circumferential direction of the base material 280. It is pressed against the portion 270.

Further, in the above embodiment, two selvage portions 66B are formed on the grounding member 64, but one may be one or three or more may be formed. In the case of a plurality of pieces, the decrease in roundness is suppressed by arranging them at the same intervals in the circumferential direction of the base material 80.

10 Image forming device 18 Image forming unit 26 Image holding body 36 Developing device 38 Charging member 46 Secondary transfer roll (example of transfer member)
60 Thick part 66B Ear part (example of pressing part)
72 Step 74 Development roll 76 Adjustment roll 80 Base material 80A Inner peripheral surface 84 Closing member 86 Photosensitive layer 260 Thick part 270 Other thick part 280 Base material

Claims (6)

With a metal cylindrical base material,
The pressing portion pressed against the inner peripheral surface of the base material,
With a photosensitive layer formed on the outer peripheral surface of the base material,
In the base material, the thickness of the portion pressed by the pressing portion is a thick portion that is thicker than the thickness of the other portion, and the thick portion is a portion in the circumferential direction of the base material. Is formed so as to extend in the circumferential direction of the base material when viewed from the axial direction of the base material, and is formed only on one side portion of the base material in the axial direction.
The step caused by the difference in the thickness of the base material is formed only on the inner peripheral surface of the base material.
The pressing portion is an image holder that is pressed against the inner peripheral surface of the axial end portion of the base material. The inner peripheral surface of the base material is not formed with a recess for reducing the thickness of the other portion of the base material.
The pressing portion has a plate shape, a cantilever shape, and a rectangular shape, and one side of the free end is pressed against the inner peripheral surface of the one end portion in the axial direction in the base material.
The image holder according to claim 1, wherein the thickness of the thick portion is not more than twice the thickness of the other portions. A plurality of the thick portions are formed, and the thick portion is formed.
Apart from the thick portion, in the base material, another thick portion having a thickness higher than the thickness of the other portion is partially formed in the circumferential direction of the base material. And
The shape of the thick portion and the shape of the other thick portion are the same, and the thick portion and the other thick portion are arranged at similar intervals in the circumferential direction of the base material. The image holder according to claim 1 or 2. The image holder according to any one of claims 1 to 3 and the image holder.
A charging member that charges the outer peripheral surface of the image holder, and
A developing member that develops an electrostatic latent image formed by exposing the outer peripheral surface of the charged image holder as a toner image, and a developing member.
An image forming unit comprising. The image forming unit according to claim 4 and
A transfer member that transfers a toner image formed on the outer peripheral surface of the image holder to a recording medium, and a transfer member.
An image forming apparatus comprising. The image holder according to any one of claims 1 to 3 and the image holder.
A charging member that charges the outer peripheral surface of the image holder, and
A developing device that develops an electrostatic latent image formed by exposing the outer peripheral surface of the charged image holder as a toner image, and a developing device.
A transfer member that transfers a toner image formed on the outer peripheral surface of the image holder to a recording medium, and a transfer member.
An image forming apparatus comprising.

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